Sheet-feeding mechanism for platen printing presses



Jan. 17, 1939 s THQMPSON 2,144,037

SHEET-FEEDINGMECHANISM FOR PLATEN PRINTING PRESSES Filed May 21, 1957 Patented Jan. 17, 1939 UNITED STATES PATENT OFFHCE SHEET-FEEDING MECHANISM FOR PLATEN PRINTING PRESSES Manchester, England Application May 21, 1937, Serial No. 148,889 In Great Britain May 23, 1936 4 Claims.

This invention has reference to sheet-feeding mechanism for platen printing presses wherein a pile of sheets to be printed is arranged in front of the movable platen and the sheets are lifted and fed on to the platen by means of a sucker or suckers acting along their front edges.

In sheet-feeding arrangements of the type referred to, the sheet is lifted by the sucker or suckers during the fall or return movement of the platen, fed on to the platen and to the lays during the stationary or comparatively slow-moving open period of the platen and registered by the lays during the lift or forward movement of the platen, the sucker mechanism meanwhile returning ready to take the next sheet.

In any sheet-feeding arrangement the object must be to lay the sheet fiat upon the platen and to place it as accurately as possible against the lays. The sheet should, therefore, be made to slide along close to the platen for the great part of its travel so as to exclude air from beneath it, and the travel should not vary from sheet to sheet. The mechanism, in particular, should be rigidly held at the moment when the suckers deposit the sheet against the lays and it should also be such as not to impede the operator in his access to the platen when the press is at rest.

The object of the present invention is to provide an improved sheet-feeding arrangement having the desirable characteristics indicated.

In a sheet-feeding arrangement according to the invention, the sucker or suckers is or are adapted to reciprocate to and fro to carry the front edge of a seized sheet to the lower edge of the movable platen and against the lays and after releasing the sheet to return to normal position, and to be also oscillated relatively to and with the platen in such manner that during its or their feeding movement it or they (the sucker or suckers) first carry the front edge of the sheet away from and then close to and along the face of the platen, and during its or their return movement it or they move well clear of the face of the platen.

The invention is hereinafter fully described with reference to the accompanying drawing in which Fig. 1 is a fragmentary more or less diagrammatic side elevation of a platen printing press comprising one embodiment of it, Fig. 2 is a fragmentary elevation looking on the left hand side of Fig. 1 and Fig. 3 is a fragmentary plan of Fig. 1. On the drawing only those parts necessary for elucidation of the invention are illustrated.

Referring to the drawing, 4 indicates the frame (Cl. MIL-28'?) of the machine, 5 indicates the stationary platen that carries the type, E3 indicates the movable platen upon which the sheets to be printed are fed, said platen being shown in its raised or printing position in full lines, and in its lowered 5 position in dotted lines, l indicates a pile of sheets to be printed carried on a support 8 arranged at the front of the machine.

On an extension of the fulcrum shaft 9 on which the movable platen 6 oscillates is pivotally 10 mounted a guide or housing it in which a slide bar H is mounted to slide between anti-friction rollers I2. At its outer or upper end the slide bar it carries a suction tube E3 on which are provided suction nozzles w and which is connected 5 with a source of suction in the usual way.

The guide or housing 45 is adapted to be oscillated on the fulcrum shaft 5. For this purpose the guide or housing 53 has connected to it at M one end of a link ill the other end of which is 20 connected to one arm Et of a bell-crank lever 55 pivoted at I? in the frame of the machine and having its other arm it provided with a bowl which engages in a cam groove i3 formed in one face of a cam disc 18. The cam disc 58 is mount- 25 ed on a shaft l9 and is adapted to be rotated by any suitable means in the direction indicated by the arrow 58 to make one revolution for each Complete operation (i. e. rise and fall) of the movable platen 6. 30

The slide bar it is adapted to be reciprocated in the guide or housing iii by means of a connecting rod 263 one end of which is pivoted to the guide or housing at it and the other end of which is pivoted at 28 to a crank 2! mounted 35 on a stub axle 22 and adapted to be oscillated through from the position shown in full lines in Fig. l to the position shown dotted lines and vice versa. The oscillations of the crank 2| are effected by means of a pinion 23 fixed to 40 the boss of the crank and with which gears a quadrant 26 on one arm 25 of a bell-crank lever 25 (also mounted on the pivot I?) the other .arm 25 of which lever is provided with a bowl which engages in a cam groove ifi formed in 45 the other face of the cam disc l3. In Fig. l a portion of the arm 25 of the bell-crank lever 25 is shown below the arm 55 of the bell-crank lever is but it will be understood that with the parts in the positions shown in Fig. 1 the arm 50 25 lies immediately behind the arm EN.

The cam grooves it and 18 are shaped as illustrated in Fig. 1 so that when the movable platen 6 is in the raised or printing position shown in full lines, the slide bar II is out of line with 55 said platen and is in its extreme outer or upper position with the suction tube E3 in position to pick up the top sheet on the pile 1. Following a pause of the platen at the printing position, the platen descends and during the first portion of its descent the printed sheet is removed from the platen by the usual delivery mechanism. During the pause and the first portion of the descent the bowls on the arms W and 25 of the bell-crank levers iii and 25 traverse the concentric portions between the points 26 and 27 of the cam grooves it and l 8* in the cam disc and there is no movement of either the guide or housing H1 or the slide bar ii. During the continued descent of the platen 5 the bowl on the arm I 6 of the bell-crank i6 traverses the cam groove from the point 27 to the point 28 and causes the bell-crank lever IE to rock the guide or housing lfi on the fulcrum shaft 9 in a counterclockwise direction as viewed in Fig. 1, then from the point 28 to the point 29 causing the bellcrank lever l6 to rock the guide or housing iii in the opposite direction back to its original position and finally from the point 29 to the point 38 during which traverse there is no rocking of the guide or housing is relatively to the platen 5. Simultaneously, with the described traverse of the bowl on the arm W of the bell-crank lever 16 from the point 21 to the point 39, the bowl of the arm 25 of the bell-crank lever 25 traverses the cam groove l8 from the point iii to the point 3! and causes the bell-crank lever, through the quadrant 2 and pinion 23, to oscillate the crank 2! through 180 from the position shown in full lines to the position shown in dotted lines. This oscillation of the crank 25, through the connecting rod 25, reciprocates the slide bar it and with it the suction tube is, inwardly or downwards. During the first portion of the subsequent rise of the platen the bowl on the arm 85 of the bell-crank lever 56 first traverses the cam groove Ili from the point as to the point 82 whereby the bell-crank lever is operated to rock the guide or housing it) counter-clockwise, and

, then from the point 32 back to the point 25 whereby the bell-crank lever is caused to restore the guide or housing to its original position. Simultaneously, the bowl on the arm 25 of the bell-crank lever 25 traverses the cam groove Ni from the point 2! back to the point 25 and the bell-crank lever 25 is operated to oscillate the crank 2! from the position indicated in dotted lines back to the position shown in full lines which oscillation of the crank, through the connecting rod 29, reciprocates the slide bar H outwards or upwards back to the position. As a result of the described rocking movements of the guide or housing ill and reciprocation of the slide bar H, the suction tube [3 moves in the path indicated by the arrow-headed dotted line 33 in Fig. 1, during the last part of the descent of the platen 6 and the initial part of its subsequent rise. Thus, as the platen 6 approaches the position shown in dotted lines in Fig. 1, the suction tube rises above the line or level of the platen, carrying with it the sheet seized from the pile l, and during the continued descent of the platen the suction tube carries the sheet above or over the platen, towards and on the platen, and down same to the lays, whereupon the sheet is released by admitting air into the suction tube in the usual way. During the initial portion of subsequent rise of the platen 6, the suction tube moves away from the platen and also upwardly and outwardly and then returns to its initial position ready to take the next sheet on the pile I.

It will be noted when the slide bar I I is in both its extreme outer or upper position and its extreme inner or lower position and the crank 2| is in its corresponding positions shown in full and dotted lines, respectively, the three centres 28*, 20 and 22 lie in a straight line thus giving positive or locked positions to the suction tube l3 and the suckers l3 I claim:-

1. In a platen printing press of the type described, a sheet-feeding mechanism comprising in combination suckers for picking up a sheet of paper, means for moving the suckers from a position to engage a sheet adjacent the outer edge of the platen to a position adjacent the inner edge thereof, said means including a pivotally mounted guideway, a bar slidably mounted in the guideway, and means for reciprocating the bar in the guideway comprising a crank and a connecting rod pivotally secured at one end to the crank and at the other end to the bar, the two pivots of the connecting rod being aligned with the crank in the two extreme positions of the suckers.

2. In a platen printing press of the type described, a sheet-feeding mechanism comprising in combination suckers for picking up a sheet of paper, means for moving the suckers from a position to engage the sheet adjacent the outer edge of the platen .to a position adjacent the inner edge thereof, said means including a pivotally mounted guideway, a bar slidably mounted in the guideway, means for reciprocating the bar in the guideway, and means for oscillating the guideway.

3. In a platen printing press of the type described, a sheet-feeding mechanism comprising in combination suckers for picking up a sheet and delivering it to the platen of the printing press, and means for reciprocating the suckers from a position adjacent the outer edge of the platen to a position adjacent the inner edge of the platen including a pivotally mounted guideway, a bar slidably mounted in the guideway, means for re- L,

ciprocating the bar in the guideway comprising a crank and a connecting rod pivotally secured to the crank and to the bar, the crank and connecting rod being arranged such that the center of rotation of the crank and the centers of the two pivotal connections of the lever are aligned in the A extreme positions of the suckers, and means for oscillating the guideway.

4. In a platen printing press of the type described, a sheet-feeding mechanism comprising in combination suckers for picking up a sheet and delivering it to the platen of the printing press, and means for reciprocating the suckers from a position adjacent the outer edge of the platen to a position adjacent the inner edge of the platen including a pivotally mounted guideway, a bar slidably mounted in the guideway, means for reciprocating the bar in the guideway comprising a crank and a connecting rod pivotally secured to the crank and to the bar, the crank and the connecting rod being arranged such that the center of rotation of the crank and the centers of the two pivotal connections of the lever are aligned in the extreme positions of the suckers, and means for oscillating the guideway including a cam and cam follower.

FRANK SYDNEY THOMPSON. 

